P0337: Crankshaft Position Sensor A Circuit Low (Meaning, Causes, Fixes)

What P0337 means

The crankshaft position sensor (CKP) reports engine speed (RPM) and crankshaft position to the engine computer (PCM), which uses it to time the spark and fuel delivery. It sits very close to a toothed reluctor ring on the crankshaft, and the teeth passing the sensor create a voltage pattern the PCM reads. OBD-Codes.com explains that the PCM constantly compares the crank signal with the camshaft sensor signals, and that P0337 is stored when the crank sensor's input voltage is lower than expected. RepairPal describes the code more broadly, saying it sets when the PCM detects an irregular signal or no signal, and notes that on older vehicles the sensor may be built into the distributor. P0337 is the 'low' code for crank sensor 'A'; P0335 is the general circuit fault, P0336 is range/performance, and P0338 and P0339 cover a high and an intermittent signal. RepairPal's P0337 page gives the meaning and severity but no symptom or cause list, so the symptoms, causes and test steps below come from OBD-Codes.com.

Severity: can I keep driving?

Stop and fix promptly

Treat this as serious. RepairPal rates P0337 'Urgent', and OBD-Codes.com calls it severe: the engine will likely not run, and even if it starts there is a high risk of a no-start. Don't count on the car until it's fixed.

Common symptoms

• Check engine light on
• Engine won't start
• Tachometer shows no RPM while the engine is cranking
• Hesitation on acceleration
• Poor engine performance
• Worse fuel economy

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

1. Failed crankshaft position sensor
2. Open or shorted wiring to the crank sensor
3. Corroded connector, or one soaked with oil, coolant or power steering fluid
4. Faulty engine computer (PCM) or a PCM programming error (less common)

Diagnostic steps you can do

1. Read all stored codes and freeze-frame data and write them down; it helps if the fault turns out to be intermittent.
2. Look over the crank sensor wiring and connector. OBD-Codes.com points out that engine oil, coolant or power steering fluid can break down wire insulation and cause shorts or opens, so look closely at anything that's been soaked.
3. Crank the engine while watching the tachometer or the RPM reading on a scan tool. No RPM while cranking points to a missing crank signal.
4. With the connector unplugged, check for the reference voltage (often 5 volts, but confirm your vehicle's spec) and a good ground at the sensor connector.
5. If you have the service manual's resistance spec, test the sensor with a multimeter and replace it if it's out of spec. Specs vary by vehicle, so don't use a generic number.

Typical fixes

• Repair open or shorted wiring, or clean or replace a corroded or fluid-damaged connector
• Replace the crankshaft position sensor if testing shows it has failed (OBD-Codes.com notes some manufacturers recommend replacing crank and cam sensors as a set)
• Check for technical service bulletins for your vehicle
• Have the PCM tested, reprogrammed or replaced only after the sensor and wiring check out

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

Related codes

• P0336 Crankshaft Position Sensor "A" Circuit Range/Performance
• P0338 Crankshaft Position Sensor "A" Circuit High
• P0335 Crankshaft Position Sensor "A" Circuit Malfunction
• P0339 Crankshaft Position Sensor "A" Circuit Intermittent
• P0340 Camshaft Position Sensor "A" Circuit Malfunction

Also listed in this guide:

All Cam/crank timing & sensor codes →

FAQs

Sources

1. OBD-Codes.com: P0337 Crankshaft Position Sensor A Circuit Low (Stephen Darby, ASE)
2. RepairPal: P0337 Crankshaft Position Sensor "A" Circuit Low (rated Urgent)